EP0374805B1 - Electronically commutated synchronous driving motor - Google Patents

Description

The invention relates to an electronically commutated synchronous motor in the form of a linear or rotary actuator according to the preamble of patent claim 1.

An electronically commutated synchronous motor of this type is described in EP-A-152508. This known synchronous motor drive has a rotatably mounted permanent magnet as the drive or actuator element; the drive element can also be a linear permanent magnet actuator, so that a linear motor is formed. In this known synchronous motor drive, the stator is formed from a winding, as a result of which an electronically generated multiphase alternating current is required for actuation. The electronic control circuit with power semiconductors required as a result has hitherto represented a certain effort which, compared to mechanically commutated direct current motors such as those e.g. in "etz, Vol. 106, Issue 20, electrical miniature motors, H. Moczala" have more than outweighed lower manufacturing costs, with the result that up to now 500 W, which is of great importance for servo drives, has so far the mechanically commutated DC motor dominates.

Due to the progressive miniaturization and integration density, electronic commutator circuits are however becoming ever cheaper, so that the Use of generic electronically commutated motors is being considered. This applies in particular to applications in which the limitation of the speed, the torque, the service life and the reliability specified by the brush commutator system cannot be tolerated in mechanically commutated direct current motors.

Among the mechanically commutated direct current motors, the bell-armature motor in particular has advantages that have so far been difficult to achieve with electronically commutated motors. Some of these advantages of the bell-armature motor, as described, for example, in "Low-inertia DC servomotors for fast movements, construction, elements, methods, II. 10/1975, M. Heyraud" are e.g. the linear characteristic, the low starting voltage, the lack of a holding torque as well as hysteresis and eddy current losses, small electrical and mechanical time constants and in particular the very small torque fluctuations.

For the use of the electronically commutated motors according to the invention as servo drives, the smallest possible fluctuation in torque is of the greatest importance. Attempts have therefore been made to make progress in this regard.

For example, in "Feinwerktechnik und Messtechnik 88 (1988), No. 4, an electronically commutated disc motor with samarium-cobalt magnets, J. Lindner", it is proposed to equip the armature with wire windings and to imprint it with a rectangular phase voltage. A relatively high concentricity or low torque fluctuations are achieved by using ironless windings with a high number of phases with weak chord or winding distribution. Such a concentrated winding has a high number of phases However, the disadvantage that a great effort is required for the control electronics, since each phase with at least one, usually. however two or four circuit breakers must be commutated. A reduction in the number of phases while the winding concentration remains the same, like a stronger winding chord, requires less efficiency if good concentricity is to be achieved. From the above-mentioned publication (J. Lindner) it can further be seen that, for example in the case of a B-phase disc rotor motor when the winding is very long, the permissible angular range for the block values of the rectangular control becomes very small if a high concentricity is aimed for. In contrast, in the case of a B-phase concentrated winding, a large area of the available air gap remains copperless. In both cases, unsatisfactory engine utilization is inevitable.

In motors that are equipped with grooves other than the generic drive, measures are known to improve the concentricity. For example, in "Electrical Machines, Vol. 1-3, VEB-Verlag Technik Berlin, 1979, G. Müller" it is proposed to skew the iron sheet package and make a groove division, in "Valvo Reports, Vol. 20, II., Permanent Magnetic Pole Sensitivity in DC motors with Ferroxdure segments, J. Koch ", there is a hint to carry out a suitable design of the magnetic forms, whereas in" Bosch technical reports, volume 4 (1973), booklet 3, the reduction of the flux fluctuation in small DC motors, A. Mohr " a corresponding design of the groove-tooth or pole shoe geometry is suggested.

In addition to the fact that these known measures are often not sufficient for more demanding concentricity requirements, a further disadvantage of the known motors is that the grooving results in a relatively high production outlay.

From EP-A-0 152 508 it is known to provide a brushless synchronous motor with a winding which consists of a multilayer winding with a plurality of turns of constant strength.

EP-A-0 133 571 describes a flat rotary motor which has a rotor with two permanent magnets and an armature winding which has several layers of essentially radially extending conductors. Here, the axial thickness of each conductor of the outermost layer in the effective range (between the two radially inner and outer conductor ends) is chosen to be less than the thickness of the conductors in the middle layers. This is to improve heat dissipation and thus cooling the armature winding and to reduce the axial air gap of the motor with unproblematic producibility.

From US-A-4 228 384 a motor with a four-layer armature is known, which is equipped with a digital position transmitter. The individual turns of the armature winding have a conventional shape.

The invention has for its object to develop an electronically commutated synchronous motor according to the preamble of claim 1 such that excellent concentricity can be achieved with reasonable manufacturing costs.

This object is achieved with the measures specified in claim 1.

According to claim 1 it is accordingly provided to form the winding from at least one printed or stamped multilayer winding. It is thereby achieved that, for example, by experiments or by means of a program explained later, a winding course can be generated which ensures a high concentricity. Due to the relatively simple manufacture of such a multilayer, the manufacturing effort is not increased in comparison to the prior art; on the contrary, the production costs can even be reduced, since suitable machines can be used to easily produce several windings in parallel by placing a large number of individual windings together a benefit is arranged, which consequently go through the same etching or galvanic manufacturing processes and can then be easily separated from the benefit. Furthermore production by companies specializing in printed circuit board production is also an option, which may result in a further cost reduction.

It is also possible to integrate a high-resolution angle sensor on the multilayer. Other electronic components, such as parts of the control circuit of the sensor or the power electronics, can also be integrated on the multilayer; this ensures that an extremely compact and reliable drive is available.

Furthermore, the formation of the winding as a multilayer in the form of a printed or punched circuit makes it possible to practically completely eliminate the noise development of the wires of the winding, which is disadvantageous in the prior art and is caused by the clocking, which can be attributed to the electromagnetic forces, since adjacent conductor tracks are spatially separated from one another and are attached to a vibration-damping plastic or glass fiber carrier. The relatively high outlay for winding machines and for assembly can also be significantly reduced. Finally, the printed or stamped circuit enables the conductor track widths to be varied in the manner indicated, so that even better motor utilization, increased efficiency and a more uniform concentricity can be achieved.

Since, as already explained, the effort for the control electronics in comparison to the manufacturing costs is constantly taking a back seat, the improved synchronization is achieved without the manufacturing costs of the overall system being significantly increased compared to the generic devices.

Furthermore, the integration of a high-resolution angle sensor or additional other sensors or sensors can be provided, for example, by integrating circuit components of the same directly onto the multilayer or by the rotor disk simultaneously taking over the function of a carrier for parts of the sensor. This enables a space-saving overall construction to be implemented.

Further advantageous developments of the invention are the subject of the other subclaims, whereby tests have shown that an embodiment of the motor which has the essential features of these claims is superior to comparable bell-armature motors with regard to quality of synchronization, torque fluctuation and efficiency.

• Fig.1: zwei Ausführungsformen des magnetischen Rückschlußjoches, nämlich
  • a) einen massiven Rückschluß in Form eines Eisenjochs bzw. einer Trägerplatte für den Permanentmagnetrotor;
  • b) einen geblechten ringförmigen Rückschluß als Träger für die Statorwicklung;
• Fig.2: anhand eines Querschnitts eine Ausführungsform der Erfindung in Form eines Synchronmotors mit integriertem optischen Dreikanal-Encoder;
• Fig.3: Ätzmasken einer inkrementalen Encoderscheibe, die zwei um 90 Grad versetzte Strichrasterblöcke sowie eine Referenzmarke aufweist;
• Fig.4: die Vorderseite des Leiterbahnbildes einer Wicklungsebene einer 8-poligen 5-Phasen-Evolventenwicklung;
• Fig.5: die Vorderseite des Leiterbahnbildes einer Wicklungsphase einer 12-poligen 3-Phasen-Spiralwicklung;
• Fig.6: eine Spiralwicklungsphase mit verbreiterten Leiterbahnführungen außerhalb des magnetischen Luftspaltfeldes.
• Fig.7: in einem Explosionszeichnungs-Querschnitt einen Wicklungs-Multilayer;
• Fig.8: Ätzmasken einzelner Multilayerschichten einer Phase, nämlich a) der Oberseite und b) der Unterseite;
• Fig.9: Ätzmasken einer Elektronik-Trägerfolie mit einer Wicklung zur Temperaturbestimmung;
• Fig.10: ein Ausführungsbeispiel, bei dem ein ohmsches Leitplastikpotentiometer als Lagesensor integriert ist;
• Fig.11: anhand eines Blockschaltbilds eine elektronische Ansteuerungsschaltung des Motors; und
• Fig.12: anhand eines Blockschaltbildes den Einsatz eines Leitplastik-Potentiometers als Signalgeber.

The invention is explained below with reference to the description of exemplary embodiments in the form of disc motors with reference to the drawing. Show it:

• Fig.1: two embodiments of the magnetic yoke, namely
  • a) a massive inference in the form of an iron yoke or a carrier plate for the permanent magnet rotor;
  • b) a laminated ring-shaped yoke as a carrier for the stator winding;
• 2: based on a cross section, an embodiment of the invention in the form of a synchronous motor with an integrated optical three-channel encoder;
• 3: etching masks of an incremental encoder disc which has two line grid blocks offset by 90 degrees and a reference mark;
• 4: the front of the conductor track image of a winding level of an 8-pole 5-phase involute winding;
• 5: the front of the conductor track image of a winding phase of a 12-pole 3-phase spiral winding;
• Fig. 6: a spiral winding phase with widened conductor tracks outside the magnetic air gap field.
• 7: in an exploded cross-section a winding multilayer;
• 8: etching masks of individual multilayer layers of a phase, namely a) the top and b) the bottom;
• Fig. 9: Etching masks of an electronic carrier film with a winding for temperature determination;
• 10: an embodiment in which an ohmic conductive plastic potentiometer is integrated as a position sensor;
• 11: an electronic control circuit of the motor based on a block diagram; and
• Fig. 12: Using a block diagram, the use of a conductive plastic potentiometer as a signal generator.

• a) Integration eines hochauflösenden 3-Kanal-Encoders mit 500 Impulsen pro Umdrehung für anspruchsvolle Positions-, Drehzahl- und Drehmoment-Regelantriebe;
• b) Integration eines hochauflösenden Leitplastikpotentiometers, das besonders für Anwendungen mit großem Temperaturbereich geeignet ist;
• c) Integration eines Minimalencoders, sowie einer Steuer- und Leistungselektronik in SMD-Technik für einfache, sehr verlustarme DC-Steuerungen, wie Batterieantriebe;
• d) zusätzliche Integration einer Temperaturmeßsonde direkt auf der Wicklung;
• e) zusätzliche Integration der Ansteuerschaltung auf der Wicklung oder im Motorgehäuse.

The exemplary embodiment of the motor according to the invention is essentially characterized by the problem solution explained below: Creation of a 3-phase synchronous motor with electronic control in three versions:

• a) Integration of a high-resolution 3-channel encoder with 500 pulses per revolution for demanding position, speed and torque control drives;
• b) Integration of a high-resolution conductive plastic potentiometer, which is particularly suitable for applications with a wide temperature range;
• c) Integration of a minimum encoder, as well as control and power electronics in SMD technology for simple, very low-loss DC controls, such as battery drives;
• d) additional integration of a temperature measuring probe directly on the winding;
• e) additional integration of the control circuit on the winding or in the motor housing.

The most important operating parameters of the motor according to the invention are an extremely high concentricity, a small motor control check, a high efficiency, a high nominal torque, low idling losses (battery operation) and a linear characteristic.

Basic design principles result from the requirements mentioned, the most important of which are explained below.

For a favorable design of the magnetic circuit, it is advisable to choose at least one dimension of the motor to be particularly small compared to the others. For cylindrical motors with radial or diametrical magnetization, the best results in terms of magnetic control and winding utilization are achieved if the motor length is chosen to be as large as possible compared to the motor diameter. The situation is reversed for flat motors with axial magnetization. Here the ratio of motor length to diameter should be as small as possible. In view of the possibility of integrating a high-resolution encoder (large diameter), as well as integrating control and power electronics, the flat design is ideal.

The flat motors offer great design advantages for numerous applications, but are available to a much lesser extent industrially than the cylindrical version.

While commutator motors make multi-pole magnet excitation difficult due to a complicated and therefore expensive brush system, this degree of freedom can be fully exploited with the synchronous motor. A multi-pole version leads to smaller soft magnetic yoke cross sections and a favorable ratio of active winding length to total winding length. The limits regarding the choice of the number of poles are given by the increasing magnetic stray fields and eddy current or hysteresis losses. Magnetic field calculations lead to the optimal number of poles under the given boundary conditions. A detailed description of this can be found in dissertation No. 8745, ETH Zurich, "Contributions to the design of permanently excited small motors of high concentricity", W. Amrhein.

An important aspect for engine development is the constructive design of the yoke, two possible principles are shown in Figure 1, namely a) a rotor-side iron yoke and b) a stator-side iron yoke.

Both principles are useful and have their advantages and disadvantages; Depending on the objective, one will choose one or the other variant. To make a selection, the main advantages and disadvantages of the two systems are compared in Table 1. Decisive for the choice of the rotor-side inference are essentially that the magnetic circuit is free from eddy current and hysteresis losses, the utilization of the soft magnetic material is considerably better than with stator-side inference and the noise with clocked motor control is eliminated.

Depending on requirements, several rotor and stator elements can be mechanically connected in series, whereby two adjacent identical elements can be combined to form one element, e.g. two adjacent yoke washers.

The design of the permanent magnet assembly can also vary. On the one hand, it is possible to manufacture the magnetic segments and then to join them together, for example on a carrier; on the other hand, you can also manufacture a magnetic ring and magnetize the desired magnetic pole configuration. The magnetic ring can be self-supporting or mounted on a carrier plate.

In order to completely switch off permanent magnetic cogging torques, which are caused by the use of the stator, the servo motor according to the invention is equipped with an ironless one Flat winding equipped. This eliminates additional problems such as tooth saturation, increased anchor reaction or groove bevel. Various solutions can be implemented with regard to the winding design.

The winding is realized by using the punched or printed technology. In consideration of the objective defined in the introduction, several factors speak in favor of a multilayer structure using modern fine etching technology or using a special process which will be described later and in which the conductor tracks are built up galvanically. This results in the advantages of an additional degree of freedom (variable conductor cross-section, which is particularly interesting for the flat winding), a simple integration of the electrical circuit of the angle encoder and the temperature sensor directly on the winding print, of contact-free conductor tracks (thus no noise development with clocked winding feed), which Achievement of relatively high fill factors and simple manufacture and assembly.

2 shows the construction of the micro-synchronous motor. The winding multilayer is located in the center of the motor. This is divided into four layers: the three winding phases and one layer for the transmitter-side SMD circuit with an integrated temperature sensor.

The winding 3 is enclosed on both sides by a symmetrical flat rotor 1. The rotor consists of two soft magnetic carrier plates 1c with high saturation induction, which are equipped with SmCo or NeFeB magnetic disks, for example. These materials currently have the highest energy density and allow, for example, a significant reduction in construction volume compared to ferrite magnets.

The optical code disk 11 is fastened on one of the two magnetic carrier plates 1c with a division of 500 lines per revolution and a reference mark (see FIG. 3). Light pulses strike the three optical sensors 14 via the diaphragm 13 (see FIG. 3), which consists of two line grid blocks offset by 90 degrees. The signal is amplified on site on the printed circuit, flank-cleaned and passed to the connection base 15. The winding phases are thus controlled synchronously with the rotor position determined from the encoder signals.

The winding 3 sits on a support ring covered with dots in the drawing. This gives the winding additional stability and can also be used for heat dissipation if, for example, it is made of a metallic material. In the latter case, it must be ensured that the conductor tracks are not short-circuited electrically.

The motor concept according to the invention requires a flat winding for the armature design, in which the winding head lies within the winding plane. The winding technology should also support the integration of an electrical circuit (SMD technology), optoelectric components for encoder function and a temperature probe. In this regard, a multilayer winding version is available as a printed circuit. Preliminary tests showed that good results can be achieved with regard to the conductor cross-sectional image.

Two variants are available for the execution of the winding structure, namely the wave winding and the loop winding. Both types of winding are shown in FIGS. 4 and 5. The first variant is an involute winding, which is named after the geometric shape of the space-saving return sections of the conductor tracks. The second variant is designed as a spiral winding. The advantages and disadvantages of this structure are compared in Table 2.

Attention to eddy current losses is of great importance in winding design. In contrast to conventional wire windings, the use of flat conductors (width / height> 1) leads to unfavorable conditions. As studies in the above-mentioned dissertation show, careful selection of the conductor path width is necessary, especially with high-pole magnetic circuits and high rotor speeds. In contrast to the spiral winding, in the involute winding the measurement-critical plated-through holes are located on the inner radius of the winding and thus determine the minimum conductor track width.

In order to keep the eddy current losses as small as possible, especially in the case of high-pole or high-speed drives, the conductor tracks in the area of the air gap field should not widen in the direction of larger radii. While this does not cause any problems in the spiral winding, this measure leads to a poor copper fill factor in the involute winding, since here the number of conductors is independent of the radius. Another advantage of spiral winding is the additional degree of freedom with regard to the conductor track geometry. Great importance is attached to this point, which will be dealt with below.

The manufacturing costs are essentially influenced by the type and number of vias. While the number of vias required for the involute winding corresponds to twice the number of conductor tracks, half of which lies on the dimensionally critical inner radius of the winding, is located on the Spiral winding only a number of vias corresponding to the number of poles, the arrangement of which in the center of the spiral is completely uncritical with regard to the space requirement.

Different degrees of freedom for the design of the spiral winding are described in the following.

The integration of, for example, a high-resolution optical angle encoder in the motor housing inevitably leads to an enlarged overall motor diameter. The additional space available is used to generate torque by means of an adapted winding design. This is done by increasing the winding diameter and, on the other hand, by varying the conductor track width within the winding structure. Conclusions for turns that lie outside the magnetic air gap field and therefore do not generate eddy current braking torques are carried out in a broadened form. These measures result in an increase in the conductor path density, an extension of the radial (torque-generating) conductor tracks, a reduction in the winding head resistance, better motor utilization and higher efficiency.

The measures mentioned can be seen in FIG. 6. The conductor tracks are additionally reinforced on the innermost spiral loop, namely on the inside diameter and on the outside diameter of the winding print. These measures are necessary to compensate for the increased attack of the etching medium on one-sided free-standing tracks. The widening of the outermost inference takes place especially in view of a cheaper clamping option of the multilayer.

If one assumes the assumption that the conductor track width in the magnetic air gap field should be constant, then with a dianetrical conductor track distribution, as shown for example in FIGS. 5 or 6, a higher conductor track density and a higher fill factor than with a radial arrangement are achieved the leader. The non-torque-generating feedback is expediently carried out inside and outside by circular arcs.

Another degree of freedom to influence the motor operating properties is the chord of the winding. The chord of the winding in the arrangement shown in FIGS. 5 and 6 is determined by the distribution of the spiral windings within an electrical pole. The further the spiral turns lead inwards to the center of the pole, the more the winding is longed for. If you are satisfied with just a few spiral turns on the outer edge of the pole, then the winding is weakly craved and even unsighted if you wind around the pole edge. Given the current curve shape given as a function of the rotor position and the magnetic field characterized by the permanent magnetic arrangement, an optimum can be calculated for the degree of elongation of the winding and thus for the number of spiral turns leading inwards, where the angle-dependent torque fluctuations are minimal. The current coating is carried synchronously with the rotation of the rotor. The winding shown in FIG. 6 is calculated and designed for sinusoidal current waveforms. The sine curve can be generated analogously; however, it can also be approximated digitally in several stages. The higher the resolution of the angle encoder, the better the digital approximation can be realized.

mit I = Stromamplitude, φ = Rotorwinkel, Iel = elektromagnetisches Drehmoment, E = induzierte Spannung bei Drehzahl , R = Phasenwiderstand, k = aktuelle Phasennummer (1 ... n), m = Anzahl Phasen, i = Laufparameter.Of course there is also the possibility to optimize the winding and the degree of chord according to other motor parameters. An electronic torque correction can be added later be made by adapting the current curve shape as a function of the rotor position to the specified winding layout and the rotor permanent magnetic field. In this case, the necessary current curve will be determined by computer or measurement technology, normalized, saved and, when the motor is operating, the standardized current value will be read out depending on the current rotor position and multiplied by the current setpoint specified by the control variable. The required current curve depending on the rotor angle can be calculated from the following equation under the secondary condition of minimal power loss:

with I = current amplitude, φ = rotor angle, Iel = electromagnetic torque, E = induced voltage at speed, R = phase resistance, k = current phase number (1 ... n), m = number of phases, i = running parameters.

The product is fed to the motor phases via the power controller. A more detailed description of this can be found in the dissertation mentioned, a corresponding exemplary embodiment being shown in FIG. 11. According to FIG. 11, an electronic control circuit consists of a curve memory or generator 30 and an arithmetic switching unit in the form of a multiplier 31, which links the input signals with the curve amplitudes of the curve memory 30 according to predetermined functions or those determined during engine operation.

Operating curves which compensate for the torque fluctuations are stored in the curve memory 30. Depending on the symmetry of the electrical or magnetic circuit, it is necessary to save the curves separately for all phases or only for a single phase. In the latter case, several curves, each offset by the phase angle, are read out. Instead of the curve memory, signal generators can also be used, each of which generates a predefined signal curve.

The switching unit 31 links the curve amplitude values made available or generated depending on the rotor angle with the applied input signals or manipulated variables in accordance with predetermined functions.

Depending on the respective rotor angle, the current curve of the curve memory is read out and multiplied by a current amplitude iA, which is chosen so that the torque fluctuations are minimal.

If the motor in question shows a non-linear behavior, it is advisable to provide different curves for different operating areas. This can e.g. in that a curve selection switch is provided depending on the operating state of the engine, or in that the curves are changed in such a way that they are better adapted to the respective operating states. However, an adjustment can also be made by changing the setting variables.

The respective values of the current curve can either be stored in tables or calculated depending on the operating state.

The control circuit can be implemented in various ways; it can e.g. can be realized by means of hardware by analog and / or digital components or can be simulated by means of a software program.

It is also possible to superimpose a torque control or a position, speed or acceleration control on the control circuit. In the exemplary embodiment, the circuit has the structure of a cascade control. A speed controller is internally subordinate to the position controller in the motor controller 32 and a current controller 33 is subordinate to this externally.

In the case of the involute winding, the torque fluctuation can be minimized by a distribution of the winding which is adapted to the current curve shape and the magnetic field. In contrast to the spiral winding, the involute winding has uniformly wide individual windings which are designed as a wave winding; a tendon is difficult here. The winding is adjusted by distribution, namely by overlapping the individual turns by, for example, one conductor track division (= conductor track width + conductor track spacing). Since the turns are on one layer, in contrast to the spiral winding, through-contacts are necessary for each distribution.

An electronic torque correction analogous to the spiral winding is also possible with the involute winding.

Detailed information on the optimization calculations and considerations as well as on the results obtained can be found in the dissertation mentioned. A constant torque is achieved when supplying sinusoidal currents in a symmetrical 2-, 3- or multi-phase system if the induced voltage of the motor is also sinusoidal. The optimal approximation to the sinus shape is achieved by the mentioned corresponding tendon of the winding. With 3-phase systems, the presence of a third or multiple harmonics of the induced voltage does not interfere if the star point of the 3-phase winding is not connected.

Fig. 7 shows the cross section of the multilayer. It consists of a total of four double-sided copper-coated insulation layers, as well as three resin-impregnated fiberglass mats, adhesive-coated polyimide layers or other insulation layers, which serve as intermediate insulation layers and as adhesive layers at the same time. The entire assembly is pressed together under high temperature and pressure. Faithful patterns of the individual layers can be seen in FIGS. 8 and 9. The winding phases 1 (Fig. 8), 2 and 3 are identical except for an angular displacement of 30 degrees (geometric) and offset winding feeds. The electronics carrier film (Fig. 9) contains pats for the placement of SMD components and, distributed over the outer edge zone, carries a meandering winding for resistance-dependent temperature measurement. This takes place in a time-discrete and pulsed manner at freely selectable time intervals.

Since the ratio of the track spacing to the track height or the ratio of the track width to the track height is very small for the etching process, undercuts are very noticeable. In order to suppress this factor, it is possible to cover the interconnect spaces with the aid of photomasks (negative structures from FIG. 9) and to apply thin copper layers galvanically to the photomask-free areas. In the next step, another photomask can be applied, which coincides with the first and only leads to an increase in the mask. Then the first becomes galvanically Copper layer reinforced. The photo masks form the support corset for the conductor track structure, which can be realized with steep walls (flanks). The described processes can be repeated cyclically until the necessary copper height is reached. In contrast to the usual etching process, the conductor tracks have no undercut, and in contrast to conventional galvanic application processes, the conductor tracks do not show a mushroom structure, which can lead to the short circuiting of adjacent conductor tracks.

The concentricity of the motor is largely determined by the chord of the winding. This is influenced by the filling of the winding pole with conductor tracks to the center, that is, to the through-connection. For rectangular armature currents, very large free spaces will remain in the center; for sinusoidal control, the spiral is continued close to the center. The decisive factor here is the distance between the innermost radially or diametrically oriented conductor track and the radial axis through the center of the winding.

The motor is supplied with predefined current or voltage waveforms depending on the rotor position. The winding arrangement in the case of the spiral or also the involute design is expediently designed with a strong chord or with a strong distribution (reason: high motor utilization). Feeding with block-shaped (rectangular) current or voltage curves would therefore cause a comparatively high torque ripple with a small number of phases. A concentrated winding suitable for rectangular current operation would, with the proposed winding principles, result in poor copper utilization of the air gap due to the few turns concentrated on the pole edges mean. As a result, it is advisable to choose current curves for the motor supply that go beyond a single-step curve shape in the positive and negative range. A position signal must therefore be available for commutation, which permits the design of a multi-stage or even an analog current or voltage curve. For this purpose, a solution using high-resolution optical encoders with an incremental code for the best possible implementation of the ideal current or voltage curve has already been proposed. Depending on the application, it may also be useful to use optical encoders or encoders based on other physical principles (such as capacitive or magnetic) with absolute digital angle information (for example gray code) or analog information.

An angle detection by means of an ohmic conductive plastic potentiometer is shown in FIG. 10. On a carrier 25, which is fixed to the motor housing, there is a resistance track 21 and a highly conductive contact track 24. The resistance track 21 is provided with electrical connections at two or more points, so that the electrical potential follows a defined curve along this track. The angle-dependent potential curve can be influenced by several implementation options; through the use of different resistance materials, through angle-dependent changes in the cross-section of the track, through a targeted selection of the electrical connection points on the resistance covering or through an external and at the connection points electrical circuitry with active or passive components. The electrical potential of the resistance track is taken off with a grinder tap 20. In motor operation with an unlimited angular range, it is necessary to use a second grinder 23 to transmit the grinder signal retransfer highly conductive contact track back to a standing system. Both grinder taps are mechanically connected to the rotating rotor.

In order to ensure operation that is as wear-free as possible, it makes sense to tap the potential on the resistance track practically without current. This can be done, for example, via operational amplifiers connected as voltage followers.

A simplification of the circuit shown in FIG. 11 can take place according to FIG. 12 if the potentiometer does not supply an angle signal for reading out the stored current or voltage curves, but directly a signal that corresponds to the desired current or voltage curves. In this case, the resistance path must be adjusted accordingly in such a way that a potential corresponding to the required current or voltage curves is present at the grinding taps. With a 3-phase motor, the three required current or voltage curves can be directly compared using three grinders with a phase shift of 120 degrees. An arrangement with two, e.g. However, grinder taps offset by 90 degrees are also sufficient, since the three required phase currents or voltages can be calculated from these two signals.

The sensorless angle information can also be derived using the voltage induced by the rotor rotation in auxiliary coils or directly in the motor winding or by means of certain harmonics of the induced voltage. This can convey information about the angular position, direction of rotation or speed via an electrical evaluation circuit.

Due to its design and functionality, the synchronous motor is very well suited as a servo or actuator, especially for a flat installation space. It is also a good idea to select gearboxes with a flat design for gear ratios and flange them onto the engine or integrate them into the engine. Such transmissions are, for example, harmonic drive transmissions or planetary gear transmissions.

Claims (18)

1. An electronically switched synchronous motor in the form of a linear or rotary actuator the actuator element of which consists of a displaceably or rotatably mounted permanent magnet while its stator consists of a multi-layer winding, characterised in that the winding (3, 3a, 3b) consists of at least one multi-layer winding (Fig. 7), of which the radially outer non-torque-forming conductor paths are widened out outside the magnetic air gap field whereas the width of the conductor paths entering the air gap field is substantially constant.
2. A synchronous motor drive according to Claim 1, characterised in that the multi-layer winding (Fig. 7) is two or multi-phase.
3. A synchronous motor drive according to Claim 1 or 2, characterised in that the printed multi-layer winding (Fig. 7) consists of double-sidedly metal, particularly copper, coated insulating foils or plates and intermediate insulating layers for mutual insulation and at the same time mechanical connection between individual winding planes.
4. A synchronous motor drive according to Claim 3, characterised in that the conductor paths (Figs. 4 to 6, 8, 9) of the printed circuit (Fig. 7) consist of a plurality of copper layers which are layered one upon another galvanically by means of masks (Figs. 8, 9).
5. A synchronous motor drive according to one of the preceding Claims, characterised in that the winding is self-supporting and/or is connected to a supporting element (10) for stiffening it mechanically and which is particularly readily heat-conductive to dissipate any loss heat generated.
6. A synchronous motor drive according to one of the preceding Claims, characterised in that the rotary actuator is constructed as a disc rotor motor (Figs. 1, 2).
7. A synchronous motor drive in the form of a disc rotor motor according to Claim 6, characterised in that the winding (3, 3a, 3b; Fig. 5, 6) is a spiral winding.
8. A synchronous motor drive according to Claim 7, characterised in that the electrical winding poles (3, 3a, 3b; Figs. 5, 6) which are on the upper or underside of a particular winding plane are so formed by preferably at least approximately radial diametral parallel azimuthal or round portions of conductor path or wire that a pitched winding is created.
9. A synchronous motor drive according to Claim 6, characterised in that the winding (3, 3a, 3b; Fig. 4) is an involute winding.
10. A synchronous motor drive according to Claim 9, characterised in that the electrical winding poles (3, 3a, 3b) are disposed on the upper and underside of a relevant winding plane and are so formed by at least approximately radial diametral parallel azimuthal or round conductor path portions that a distributed winding is created.
11. A synchronous motor drive according to one of the preceding Claims, characterised in that the relevant winding layout is so attuned to the air gap field generated by the permanent magnet (1a; 1a, 1b) that for whichever is the imprinted current or voltage form the torque fluctuations which are dependent upon the position of the actuator element (2) assume a minimum value or come close to the attainable minimum.
12. A synchronous motor drive according to Claim 11, characterised in that the current or voltage is imprinted according to a curve form composed of individual previously-defined harmonics and corresponding particularly to a sinusoidal curve form.
13. A synchronous motor drive in the form of a disc rotor motor according to one of the preceding Claims, characterised in that a plurality of all the magnetic poles on a magnet disc (1a; 1a, 1b) are magnetised on or consist of individual magnets.
14. A synchronous motor drive according to Claim 13, characterised in that as a magnetic return for the magnetic poles a rotating iron yoke (1c) is provided which at the same time serves to carry them.
15. A synchronous motor drive according to Claim 13, characterised in that as a magnetic return for the magnetic poles, a stator is provided which is of multi-plate or solid ferrite, synthetic plastics-iron bonded or other material having low eddy current and magnetic reversal losses.
16. A synchronous motor drive in the form of a disc rotor motor according to one of the preceding Claims, characterised in that the permanent magnet rotor (1, 2) consists of a plurality of individual rotors connected to one another and disposed serially along the axis of rotation, there being associated with each individual rotor at least one winding (3; 3a, 3b) which is exposed to the air gap field thereof.
17. A synchronous motor drive according to one of the preceding Claims, characterised in that integrated onto the printed or stamped multi-layer winding (3) is at least one electric circuit for triggering the motor, for signal processing or for triggering the position sensor (11 to 14; 20 to 24), a rotary speed sensor, temperature sensor or other sensors such as in particular sensors for ascertaining optical, mechanical, thermal, electrical or magnetic magnitudes and/or at least one of these sensors.
18. A synchronous motor drive according to one of the preceding Claims, characterised in that the means mentioned in Claim 17 are integrated into the motor housing.

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